1. Field of the Invention
This invention relates to recording or reproducing apparatuses and, more particularly, to a recording medium replacement detecting device for detecting the fact that the recording medium has been replaced.
2. Description of the Related Art
The apparatus for recording pictures, sound and other items of information on a recording medium has been proposed in many forms. Yet, recently, electronic cameras are rapidly spreading, which use, for example, what is called a "video floppy disk" as the recording medium. When the video signals or audio signals are recorded, a plurality tracks are formed successively on it. After recorded, the picture or sound can be reproduced, printed out, or transmitted through the telephone line.
Since a number of items of information are recorded successively in the corresponding number of tracks on the recording medium, for such an electronic camera, it becomes a very important prerequisite that the available recording tracks on the recording medium are effectively used, while avoiding occurrence of double recording on one and the same track. In other words, there is need to do always a task that, prior to executing a recording, the recording head is accurately positioned to the unrecorded area on the recording medium.
A double recording preventing mechanism of this kind is known by employing a method that, prior to making the recording, whether or not the position to be recorded on the recording medium is fresh is examined, and, if, as the recorded information already exists in this position, this position is determined to have been used for recording, the recording head is moved to the next area. Such a procedure is repeated. Thus, the recording head finally reaches the unrecorded area. (An example of this mechanism is disclosed in U.S. Pat. No. 4,783,707.)
In the recording or reproducing apparatus of the character described above, by adopting the control sequence of, for example, a scheme that the termination of the recording in one recording area, or the actuation for the initiation of the next recording operation, is followed by the movement of the recording head to the next recording position, the present position itself of the head on the recording medium becomes equivalent to the memorizing of the next recording position for the recording medium. Therefore, even with the electric power source being turned off, or, in a case where the apparatus is of the type which can be driven by the dry battery, even with the battery being taken out for the replacement purpose by a new one, or for the recharging purpose, or further, as the actual voltage of the electric power source has fallen below the predetermined threshold level, even with battery having become unusable, when the electric power source is turned on again, or recovered, it results that for that recording medium which was used in the preceding recording, even if a recording is started from the present position of the head, no double recording takes place, provided the recording head is not moved and it also does not happen that an unnecessarily unrecorded area or vacant track is formed.
However, according to this arrangement, if the recording medium is replaced during the time when the electric power source is cut off in any way whatever, the present position of the recording head totally loses its significance. The ignorance of this in proceeding the recording, therefore, will result in either a double recording, or formation of vacant tracks, or like problems.
To cope with such situations, the locating operation of the recording head to the unrecorded area on the recording medium must be carried out, as has been described before, each time the electric power source is turned on. This implies that despite no replacement of the recording medium, every time the electric power source is turned on, it happens that the sequence of operations of detecting the unrecorded area and of locating the recording head is recycled. Hence, the real time recordation (the snap shot in terms of camera) is largely damaged. In the battery-driven apparatus, there is another drawback of premature consumption of electric energy in the battery.
In another type of apparatus, too, which, depending on the characteristic and type of the used recording medium, exchanges the recording heads and determines the values of various factors for recording, similar problems to those described above arise.
To solve such problems, a method has been proposed by using a mechanism for mechanically memorizing the replacement of the recording medium and by carrying out the re-location of the recording head according to the state of that memory mechanism (in U.S. Pat. No. 5,072,317 filed on Feb. 5, 1986).
Also, with the fact in mind that the lid of the chamber for the recording medium in the apparatus opens and closes when the recording medium is replaced, another method has been proposed in U.S. Pat. No. 4,951,276 filed on Dec. 2, 1987 where use is made of a switch as arranged to turn on at a time during the opening operation of the lid, whereby the replacement of the recording medium is detected.
However, the use of the above-described mechanical form of the means for memorizing the replacement of the recording medium in the recording medium replacement detecting device leads to an increase in the necessary number of parts. This is not only disadvantageous at the aspect of production cost, but also, because an additional mechanism for resetting the device from the mechanical memory becomes necessary, the mechanical feature gets even more complicated. Furthermore, there is even a drawback that it takes a relatively long time to carry out the resetting operation.
The switch type of replacement detecting device for the recording medium also has many problems, since, in addition to the switch for detecting when the lid is opened, there is need to use another switch which detects that the recording medium has been inserted into and seated in the chamber, yet another switch which detects that the lid is being closed, and a furthermore switch which senses the write-protect notch. This is disadvantageous on space. Further, because the switch for detecting the opened lid is associated with the complicated mechanism as has been described before, this contributes to a cause of increasing the cost.